A known production method of a catalyst ink for fuel cell includes steps of (a) mixing an electrode catalyst with water and a lower alcohol (having 4 or less carbon atoms) and dispersing electrode catalyst particles to prepare a dispersion, (b) mixing an ionomer with a solvent to prepare an ionomer solution having relative permittivity of not less than 30 at 20° C., (c) mixing the dispersion prepared in the step (a) with the ionomer solution prepared in the step (b) to obtain a fluid dispersion, and (d) mixing the fluid dispersion obtained in the step (c) with a low relative-permittivity dispersion medium having relative permittivity of not larger than 20 at 20° C., so as to increase the viscosity of the fluid dispersion.